Daily cosmobite: Jupiter’s moons, occultations and eclipses

Jupiter’s moons are clearly visible through the telescopes at Sydney Observatory.Until July Jupiter’s moons will undergo a series of mutual eclipses and occultations. These happen every six years when the orbital plane of the moons appears edge-on to Earth.

Jupiter’s moons are clearly visible through the telescopes at Sydney Observatory. This simulates the view far better than my iPhone pictures! Diagram by Nick Lomb using Stellarium.




2 responses to “Daily cosmobite: Jupiter’s moons, occultations and eclipses

  • I seen Jupiter and 4 of its moons 2 weeks ago, and surprised as I was, so happy to of seen such a site brought tears to my eyes because this was the first time that I have ever seen Jupiter and 4 of its moons. I’ve been Star gazing & moon watching for almost 2 years. However, just recently within the past year it’s become my main hobby and interest especially the moon, which intrigues me ever so much. My question is about Jupiter and it’s moons. I’ve looked at many pictures and 99% of them show 2 of its moons on one side and 2 on the other. However, the first time I seen them(May 26, 2019 apx. 10:30pn-11:00pm) it was 3 of the moons on the right side of Jupiter & one moon on the left side of Jupiter & they were all even with each other & straight across in a line-like. I know what I’m looking at. It’s clear as day (figure of speech) Then tonight (June 2nd 2019) @ apx. time starting at 10:00pm & ending at 12:00am while looking at Jupiter & it’s moons again, without a tripod it was slightly hard to hold my binoculars still (their high powered & heavy) but what I seen this time was 2 moons to the left of Jupiter and I just couldn’t see the other moons. I’m not understanding why the first time I seen what I did then this time completely different. I’m still learning. Can anyone please tell me why the differences of moons in different locations & does it change like this all the time? It’s strange that I couldn’t find one picture showing 3 moons to the right & 1 moon to the left.
    I apologize for the length of this comment, im just a very detailed kinda person. Thanks in advance. Sincerely Jen (Poppy)

    • Jen, Jupiter’s moons are moving in orbit around Jupiter, just as our Moon orbits around Earth. So at different times you will see them in different parts of their orbit. Each of Jupiter’s moons takes a different time to complete an orbit – from just a few days for the closest of the four (Io) to about 2-weeks for the moon furthest out (Callisto). Sometimes all four are visible, sometimes one is behind Jupiter. Here is a handy little program (or try here) which you can use to see how their position changes. Sometimes you will see them pop out from behind Jupiter, or maybe see the shadow of a moon pass across the face of Jupiter (this may require a telescope to see easily). The links above explain when each event will happen. You have picked a fascinating and ever-changing aspect of the skies to observe – just as Galileo did over 400 years ago!

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